Comprehensive Operation and Maintenance Strategy for Medium-Voltage Distribution Equipment Taking 12 kV Air-Insulated Ring Main Units as an Example

1. Integrated Operation and Maintenance Strategy for Medium-Voltage Distribution Equipment

To effectively prevent discharge faults in distribution equipment, it is essential to establish a corresponding operation and maintenance (O&M) strategy. This strategy should focus on air-insulated ring main units (RMUs) as the primary subject, utilizing live-line detection as a key method and aiming for closed-loop defect elimination. This approach establishes a scientific and effective closed-loop management system. Furthermore, the current maintenance strategy must be rigorously reviewed according to relevant technical standards. Any identified unreasonable aspects should be promptly revised to ensure the full effectiveness of the integrated O&M strategy.

1.1 Pollution Flashover Prevention for 12 kV Air-Insulated Medium-Voltage RMUs

For pollution flashover prevention, RTV (Room Temperature Vulcanizing) silicone rubber and RTV coatings are the primary materials used. These materials are applied thoroughly to insulators and surge arresters, forming a protective film on their surfaces. This treatment renders the equipment surface hydrophobic, effectively enhancing surface insulation resistance and preventing pollution-related issues. During coating application, the thickness must be controlled within the range of 0.4–0.6 mm to ensure optimal performance. Coatings that are too thin or too thick cannot fully realize their protective function, and the anti-pollution effect will not meet desired standards.

If certain distribution equipment exhibits significant leakage and is already in a state of insulation failure, it must be scientifically and effectively removed. For equipment still usable, appropriate retrofitting is required, including replacement of the corresponding surge arresters. After equipment replacement or retrofitting, RTV coating should be applied to achieve effective anti-condensation protection, ensuring the equipment operates without external contamination.

For equipment with corroded connection copper bars or busbars, rust should be removed immediately. After thorough cleaning, anti-corrosion coating should be applied. In cases of severe condensation, heat-shrink insulation sleeves should be used to protect the busbars, effectively preventing damage.

1.2 Comprehensive Dehumidification for 10 kV Air-Insulated Medium-Voltage RMUs

Currently, some power supply enterprises have proposed a condensation control theory and successfully developed integrated dehumidification equipment combining heating with semiconductor dehumidification. This equipment effectively performs dehumidification in practical applications, ensuring safe and efficient equipment operation. Under certain temperature conditions, high air humidity can lead to condensation, which adversely affects normal equipment operation; thus, effective dehumidification is essential.

Given the various causes and significant impact of condensation, the dehumidification process should combine semiconductor condensation technology with heating dehumidification to effectively control humid air. When the air temperature is low, the heater should be activated promptly. Once the temperature reaches a reasonable range, the system should switch to semiconductor dehumidification mode, thereby providing maximum protection for the distribution equipment.

1.3 Refurbishment and Factory-Return Maintenance Strategy

For RMUs in relatively good operating condition, damaged components can be replaced. Equipment must undergo strict testing before maintenance and can only be returned to service upon meeting standards. Currently, maintenance costs are generally high for relevant departments. To ensure corporate economic returns, maintenance costs must be controlled within 30%. Therefore, when equipment is damaged, enterprises can opt for factory-return maintenance. After successful repair, these units can serve as routine spare parts. This approach not only improves repair efficiency but also significantly reduces maintenance costs and enhances overall management.

During the refurbishment process, technical personnel must conduct an in-depth analysis of damaged insulation components. If insulation components cannot be restored to usable condition after refurbishment, they should be promptly discarded.

2. Technical and Economic Comparison

2.1 Attention State

During development, a technical and economic comparison of maintenance strategies should be conducted to effectively reduce maintenance costs for enterprises and maximize maintenance effectiveness at the lowest possible cost, ensuring adequate protection for distribution equipment. In the economic comparison, the total integrated maintenance cost must be calculated, fully considering costs at all stages. The three primary cost components are load transfer loss, construction loss, and pollution prevention fees. If the total maintenance cost is excessively high, specific cost items should be adjusted to minimize expenses without compromising the final maintenance strategy, thereby improving overall maintenance efficiency.

2.2 Abnormal State

In addition to calculating the integrated maintenance cost, the cost under abnormal conditions must also be assessed. When distribution equipment is in an abnormal state, construction loss, pollution prevention fees, and comprehensive handling costs should be summed, along with load transfer loss. After maintenance, the relevant cost under abnormal conditions is obtained by adding power outage loss, pollution prevention fees, and comprehensive disposal costs.

2.3 Severe State

In severe cases, when distribution equipment is in a critical condition, the calculation of integrated maintenance costs requires summing load transfer loss, construction loss, factory-return maintenance costs, and retrofit construction costs. Under severe conditions, maintenance costs need only consider power outage loss, the price of new RMUs, and final retrofit construction costs. Technical personnel must fully consider the current specific development situation during economic comparisons and avoid blindly pursuing low costs to ensure maintenance efficiency.

3. Conclusion

To achieve more scientific and efficient integrated operation and maintenance for distribution equipment, the current specific development situation must be fully considered. Appropriate operational strategies should be formulated, with economic factors taken into account during implementation to minimize costs. This approach not only enhances hardware efficiency but also ensures corporate economic returns.